Localized quasiparticles in a quasi-two-dimensional fluxonium

Published

February 21, 2026

Author(s)

Trevyn Larson, Sarah Jones, Tamas Kalmar, Pablo Aramburu Sanchez, Sai Pavan Chitta, Varun Verma, Kristen Genter, Katarina Cicak, Sae Woo Nam, Gergo Fulop, Jens Koch, Raymond Simmonds, Andras Gyenis

Abstract

Disordered superconducting materials with high kinetic inductance are an important resource for generating nonlinearity in quantum circuits and creating high-impedance environments. In thin films fabricated from these materials, the combination of disorder and low effective dimensionality leads to increased order parameter fluctuations and enhanced kinetic inductance values. Among the challenges of harnessing these compounds in coherent devices are their proximity to the superconductor-insulator phase transition and the two-level systems located in the disordered structure. Here, we fabricate tungsten silicide wires from quasi-two-dimensional films and embed them into microwave resonators and fluxonium qubits, where the kinetic inductance provides the inductive part of the circuits. In this work, we study the dependence of loss on the frequency, disorder, and geometry of the devices, and find that the loss increases with the level of disorder and is dominated by the localized quasiparticles trapped in the spatial variations of the superconducting gap.

Citation

Nature Materials

Pub Type

Journals

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Keywords

Novel Superconducting Qubits, Kinetic Inductance

Citation

Larson, T. , Jones, S. , Kalmar, T. , Aramburu Sanchez, P. , Pavan Chitta, S. , Verma, V. , Genter, K. , Cicak, K. , Woo Nam, S. , Fulop, G. , Koch, J. , Simmonds, R. and Gyenis, A. (2026), Localized quasiparticles in a quasi-two-dimensional fluxonium, Nature Materials, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=959606 (Accessed April 1, 2026)